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icmp.c
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icmp.c
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/*
* NET3: Implementation of the ICMP protocol layer.
*
* Alan Cox, <[email protected]>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Some of the function names and the icmp unreach table for this
* module were derived from [icmp.c 1.0.11 06/02/93] by
* Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
* Other than that this module is a complete rewrite.
*
* Fixes:
* Clemens Fruhwirth : introduce global icmp rate limiting
* with icmp type masking ability instead
* of broken per type icmp timeouts.
* Mike Shaver : RFC1122 checks.
* Alan Cox : Multicast ping reply as self.
* Alan Cox : Fix atomicity lockup in ip_build_xmit
* call.
* Alan Cox : Added 216,128 byte paths to the MTU
* code.
* Martin Mares : RFC1812 checks.
* Martin Mares : Can be configured to follow redirects
* if acting as a router _without_ a
* routing protocol (RFC 1812).
* Martin Mares : Echo requests may be configured to
* be ignored (RFC 1812).
* Martin Mares : Limitation of ICMP error message
* transmit rate (RFC 1812).
* Martin Mares : TOS and Precedence set correctly
* (RFC 1812).
* Martin Mares : Now copying as much data from the
* original packet as we can without
* exceeding 576 bytes (RFC 1812).
* Willy Konynenberg : Transparent proxying support.
* Keith Owens : RFC1191 correction for 4.2BSD based
* path MTU bug.
* Thomas Quinot : ICMP Dest Unreach codes up to 15 are
* valid (RFC 1812).
* Andi Kleen : Check all packet lengths properly
* and moved all kfree_skb() up to
* icmp_rcv.
* Andi Kleen : Move the rate limit bookkeeping
* into the dest entry and use a token
* bucket filter (thanks to ANK). Make
* the rates sysctl configurable.
* Yu Tianli : Fixed two ugly bugs in icmp_send
* - IP option length was accounted wrongly
* - ICMP header length was not accounted
* at all.
* Tristan Greaves : Added sysctl option to ignore bogus
* broadcast responses from broken routers.
*
* To Fix:
*
* - Should use skb_pull() instead of all the manual checking.
* This would also greatly simply some upper layer error handlers. --AK
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/types.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/string.h>
#include <linux/netfilter_ipv4.h>
#include <linux/slab.h>
#include <net/snmp.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/protocol.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <net/ping.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <net/checksum.h>
#include <net/xfrm.h>
#include <net/inet_common.h>
#include <net/ip_fib.h>
/*
* Build xmit assembly blocks
*/
struct icmp_bxm {
struct sk_buff *skb;
int offset;
int data_len;
struct {
struct icmphdr icmph;
__be32 times[3];
} data;
int head_len;
struct ip_options_data replyopts;
};
/* An array of errno for error messages from dest unreach. */
/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
const struct icmp_err icmp_err_convert[] = {
{
.errno = ENETUNREACH, /* ICMP_NET_UNREACH */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
.fatal = 0,
},
{
.errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
.fatal = 1,
},
{
.errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
.fatal = 1,
},
{
.errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
.fatal = 0,
},
{
.errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
.fatal = 0,
},
{
.errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
.fatal = 1,
},
{
.errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
.fatal = 1,
},
{
.errno = ENONET, /* ICMP_HOST_ISOLATED */
.fatal = 1,
},
{
.errno = ENETUNREACH, /* ICMP_NET_ANO */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
.fatal = 1,
},
{
.errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
.fatal = 0,
},
{
.errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
.fatal = 1,
},
{
.errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
.fatal = 1,
},
};
EXPORT_SYMBOL(icmp_err_convert);
/*
* ICMP control array. This specifies what to do with each ICMP.
*/
struct icmp_control {
void (*handler)(struct sk_buff *skb);
short error; /* This ICMP is classed as an error message */
};
static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
/*
* The ICMP socket(s). This is the most convenient way to flow control
* our ICMP output as well as maintain a clean interface throughout
* all layers. All Socketless IP sends will soon be gone.
*
* On SMP we have one ICMP socket per-cpu.
*/
static struct sock *icmp_sk(struct net *net)
{
return net->ipv4.icmp_sk[smp_processor_id()];
}
static inline struct sock *icmp_xmit_lock(struct net *net)
{
struct sock *sk;
local_bh_disable();
sk = icmp_sk(net);
if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
/* This can happen if the output path signals a
* dst_link_failure() for an outgoing ICMP packet.
*/
local_bh_enable();
return NULL;
}
return sk;
}
static inline void icmp_xmit_unlock(struct sock *sk)
{
spin_unlock_bh(&sk->sk_lock.slock);
}
/*
* Send an ICMP frame.
*/
static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
struct flowi4 *fl4, int type, int code)
{
struct dst_entry *dst = &rt->dst;
bool rc = true;
if (type > NR_ICMP_TYPES)
goto out;
/* Don't limit PMTU discovery. */
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
goto out;
/* No rate limit on loopback */
if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
goto out;
/* Limit if icmp type is enabled in ratemask. */
if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1);
rc = inet_peer_xrlim_allow(peer,
net->ipv4.sysctl_icmp_ratelimit);
if (peer)
inet_putpeer(peer);
}
out:
return rc;
}
/*
* Maintain the counters used in the SNMP statistics for outgoing ICMP
*/
void icmp_out_count(struct net *net, unsigned char type)
{
ICMPMSGOUT_INC_STATS(net, type);
ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
}
/*
* Checksum each fragment, and on the first include the headers and final
* checksum.
*/
static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
struct sk_buff *skb)
{
struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
__wsum csum;
csum = skb_copy_and_csum_bits(icmp_param->skb,
icmp_param->offset + offset,
to, len, 0);
skb->csum = csum_block_add(skb->csum, csum, odd);
if (icmp_pointers[icmp_param->data.icmph.type].error)
nf_ct_attach(skb, icmp_param->skb);
return 0;
}
static void icmp_push_reply(struct icmp_bxm *icmp_param,
struct flowi4 *fl4,
struct ipcm_cookie *ipc, struct rtable **rt)
{
struct sock *sk;
struct sk_buff *skb;
sk = icmp_sk(dev_net((*rt)->dst.dev));
if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
icmp_param->data_len+icmp_param->head_len,
icmp_param->head_len,
ipc, rt, MSG_DONTWAIT) < 0) {
ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
ip_flush_pending_frames(sk);
} else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
struct icmphdr *icmph = icmp_hdr(skb);
__wsum csum = 0;
struct sk_buff *skb1;
skb_queue_walk(&sk->sk_write_queue, skb1) {
csum = csum_add(csum, skb1->csum);
}
csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
(char *)icmph,
icmp_param->head_len, csum);
icmph->checksum = csum_fold(csum);
skb->ip_summed = CHECKSUM_NONE;
ip_push_pending_frames(sk, fl4);
}
}
/*
* Driving logic for building and sending ICMP messages.
*/
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
struct ipcm_cookie ipc;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
struct flowi4 fl4;
struct sock *sk;
struct inet_sock *inet;
__be32 daddr, saddr;
u32 mark = IP4_REPLY_MARK(net, skb->mark);
if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
return;
sk = icmp_xmit_lock(net);
if (sk == NULL)
return;
inet = inet_sk(sk);
icmp_param->data.icmph.checksum = 0;
inet->tos = ip_hdr(skb)->tos;
sk->sk_mark = mark;
daddr = ipc.addr = ip_hdr(skb)->saddr;
saddr = fib_compute_spec_dst(skb);
ipc.opt = NULL;
ipc.tx_flags = 0;
ipc.ttl = 0;
ipc.tos = -1;
if (icmp_param->replyopts.opt.opt.optlen) {
ipc.opt = &icmp_param->replyopts.opt;
if (ipc.opt->opt.srr)
daddr = icmp_param->replyopts.opt.opt.faddr;
}
memset(&fl4, 0, sizeof(fl4));
fl4.daddr = daddr;
fl4.saddr = saddr;
fl4.flowi4_mark = mark;
fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
fl4.flowi4_proto = IPPROTO_ICMP;
security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
rt = ip_route_output_key(net, &fl4);
if (IS_ERR(rt))
goto out_unlock;
if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
icmp_param->data.icmph.code))
icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock(sk);
}
static struct rtable *icmp_route_lookup(struct net *net,
struct flowi4 *fl4,
struct sk_buff *skb_in,
const struct iphdr *iph,
__be32 saddr, u8 tos, u32 mark,
int type, int code,
struct icmp_bxm *param)
{
struct rtable *rt, *rt2;
struct flowi4 fl4_dec;
int err;
memset(fl4, 0, sizeof(*fl4));
fl4->daddr = (param->replyopts.opt.opt.srr ?
param->replyopts.opt.opt.faddr : iph->saddr);
fl4->saddr = saddr;
fl4->flowi4_mark = mark;
fl4->flowi4_tos = RT_TOS(tos);
fl4->flowi4_proto = IPPROTO_ICMP;
fl4->fl4_icmp_type = type;
fl4->fl4_icmp_code = code;
security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
rt = __ip_route_output_key(net, fl4);
if (IS_ERR(rt))
return rt;
/* No need to clone since we're just using its address. */
rt2 = rt;
rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
flowi4_to_flowi(fl4), NULL, 0);
if (!IS_ERR(rt)) {
if (rt != rt2)
return rt;
} else if (PTR_ERR(rt) == -EPERM) {
rt = NULL;
} else
return rt;
err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
if (err)
goto relookup_failed;
if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
rt2 = __ip_route_output_key(net, &fl4_dec);
if (IS_ERR(rt2))
err = PTR_ERR(rt2);
} else {
struct flowi4 fl4_2 = {};
unsigned long orefdst;
fl4_2.daddr = fl4_dec.saddr;
rt2 = ip_route_output_key(net, &fl4_2);
if (IS_ERR(rt2)) {
err = PTR_ERR(rt2);
goto relookup_failed;
}
/* Ugh! */
orefdst = skb_in->_skb_refdst; /* save old refdst */
err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
RT_TOS(tos), rt2->dst.dev);
dst_release(&rt2->dst);
rt2 = skb_rtable(skb_in);
skb_in->_skb_refdst = orefdst; /* restore old refdst */
}
if (err)
goto relookup_failed;
rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
flowi4_to_flowi(&fl4_dec), NULL,
XFRM_LOOKUP_ICMP);
if (!IS_ERR(rt2)) {
dst_release(&rt->dst);
memcpy(fl4, &fl4_dec, sizeof(*fl4));
rt = rt2;
} else if (PTR_ERR(rt2) == -EPERM) {
if (rt)
dst_release(&rt->dst);
return rt2;
} else {
err = PTR_ERR(rt2);
goto relookup_failed;
}
return rt;
relookup_failed:
if (rt)
return rt;
return ERR_PTR(err);
}
/*
* Send an ICMP message in response to a situation
*
* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
* MAY send more (we do).
* MUST NOT change this header information.
* MUST NOT reply to a multicast/broadcast IP address.
* MUST NOT reply to a multicast/broadcast MAC address.
* MUST reply to only the first fragment.
*/
void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
{
struct iphdr *iph;
int room;
struct icmp_bxm *icmp_param;
struct rtable *rt = skb_rtable(skb_in);
struct ipcm_cookie ipc;
struct flowi4 fl4;
__be32 saddr;
u8 tos;
u32 mark;
struct net *net;
struct sock *sk;
if (!rt)
goto out;
net = dev_net(rt->dst.dev);
/*
* Find the original header. It is expected to be valid, of course.
* Check this, icmp_send is called from the most obscure devices
* sometimes.
*/
iph = ip_hdr(skb_in);
if ((u8 *)iph < skb_in->head ||
(skb_network_header(skb_in) + sizeof(*iph)) >
skb_tail_pointer(skb_in))
goto out;
/*
* No replies to physical multicast/broadcast
*/
if (skb_in->pkt_type != PACKET_HOST)
goto out;
/*
* Now check at the protocol level
*/
if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
goto out;
/*
* Only reply to fragment 0. We byte re-order the constant
* mask for efficiency.
*/
if (iph->frag_off & htons(IP_OFFSET))
goto out;
/*
* If we send an ICMP error to an ICMP error a mess would result..
*/
if (icmp_pointers[type].error) {
/*
* We are an error, check if we are replying to an
* ICMP error
*/
if (iph->protocol == IPPROTO_ICMP) {
u8 _inner_type, *itp;
itp = skb_header_pointer(skb_in,
skb_network_header(skb_in) +
(iph->ihl << 2) +
offsetof(struct icmphdr,
type) -
skb_in->data,
sizeof(_inner_type),
&_inner_type);
if (itp == NULL)
goto out;
/*
* Assume any unknown ICMP type is an error. This
* isn't specified by the RFC, but think about it..
*/
if (*itp > NR_ICMP_TYPES ||
icmp_pointers[*itp].error)
goto out;
}
}
icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
if (!icmp_param)
return;
sk = icmp_xmit_lock(net);
if (sk == NULL)
goto out_free;
/*
* Construct source address and options.
*/
saddr = iph->daddr;
if (!(rt->rt_flags & RTCF_LOCAL)) {
struct net_device *dev = NULL;
rcu_read_lock();
if (rt_is_input_route(rt) &&
net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
if (dev)
saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
else
saddr = 0;
rcu_read_unlock();
}
tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
IPTOS_PREC_INTERNETCONTROL) :
iph->tos;
mark = IP4_REPLY_MARK(net, skb_in->mark);
if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
goto out_unlock;
/*
* Prepare data for ICMP header.
*/
icmp_param->data.icmph.type = type;
icmp_param->data.icmph.code = code;
icmp_param->data.icmph.un.gateway = info;
icmp_param->data.icmph.checksum = 0;
icmp_param->skb = skb_in;
icmp_param->offset = skb_network_offset(skb_in);
inet_sk(sk)->tos = tos;
sk->sk_mark = mark;
ipc.addr = iph->saddr;
ipc.opt = &icmp_param->replyopts.opt;
ipc.tx_flags = 0;
ipc.ttl = 0;
ipc.tos = -1;
rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
type, code, icmp_param);
if (IS_ERR(rt))
goto out_unlock;
if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
goto ende;
/* RFC says return as much as we can without exceeding 576 bytes. */
room = dst_mtu(&rt->dst);
if (room > 576)
room = 576;
room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
room -= sizeof(struct icmphdr);
icmp_param->data_len = skb_in->len - icmp_param->offset;
if (icmp_param->data_len > room)
icmp_param->data_len = room;
icmp_param->head_len = sizeof(struct icmphdr);
icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
ende:
ip_rt_put(rt);
out_unlock:
icmp_xmit_unlock(sk);
out_free:
kfree(icmp_param);
out:;
}
EXPORT_SYMBOL(icmp_send);
static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
{
const struct iphdr *iph = (const struct iphdr *) skb->data;
const struct net_protocol *ipprot;
int protocol = iph->protocol;
/* Checkin full IP header plus 8 bytes of protocol to
* avoid additional coding at protocol handlers.
*/
if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
return;
raw_icmp_error(skb, protocol, info);
rcu_read_lock();
ipprot = rcu_dereference(inet_protos[protocol]);
if (ipprot && ipprot->err_handler)
ipprot->err_handler(skb, info);
rcu_read_unlock();
}
static bool icmp_tag_validation(int proto)
{
bool ok;
rcu_read_lock();
ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
rcu_read_unlock();
return ok;
}
/*
* Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
* ICMP_PARAMETERPROB.
*/
static void icmp_unreach(struct sk_buff *skb)
{
const struct iphdr *iph;
struct icmphdr *icmph;
struct net *net;
u32 info = 0;
net = dev_net(skb_dst(skb)->dev);
/*
* Incomplete header ?
* Only checks for the IP header, there should be an
* additional check for longer headers in upper levels.
*/
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto out_err;
icmph = icmp_hdr(skb);
iph = (const struct iphdr *)skb->data;
if (iph->ihl < 5) /* Mangled header, drop. */
goto out_err;
if (icmph->type == ICMP_DEST_UNREACH) {
switch (icmph->code & 15) {
case ICMP_NET_UNREACH:
case ICMP_HOST_UNREACH:
case ICMP_PROT_UNREACH:
case ICMP_PORT_UNREACH:
break;
case ICMP_FRAG_NEEDED:
/* for documentation of the ip_no_pmtu_disc
* values please see
* Documentation/networking/ip-sysctl.txt
*/
switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
default:
LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
&iph->daddr);
break;
case 2:
goto out;
case 3:
if (!icmp_tag_validation(iph->protocol))
goto out;
/* fall through */
case 0:
info = ntohs(icmph->un.frag.mtu);
}
break;
case ICMP_SR_FAILED:
LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
&iph->daddr);
break;
default:
break;
}
if (icmph->code > NR_ICMP_UNREACH)
goto out;
} else if (icmph->type == ICMP_PARAMETERPROB)
info = ntohl(icmph->un.gateway) >> 24;
/*
* Throw it at our lower layers
*
* RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
* header.
* RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
* transport layer.
* RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
* transport layer.
*/
/*
* Check the other end isn't violating RFC 1122. Some routers send
* bogus responses to broadcast frames. If you see this message
* first check your netmask matches at both ends, if it does then
* get the other vendor to fix their kit.
*/
if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
&ip_hdr(skb)->saddr,
icmph->type, icmph->code,
&iph->daddr, skb->dev->name);
goto out;
}
icmp_socket_deliver(skb, info);
out:
return;
out_err:
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
goto out;
}
/*
* Handle ICMP_REDIRECT.
*/
static void icmp_redirect(struct sk_buff *skb)
{
if (skb->len < sizeof(struct iphdr)) {
ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
return;
}
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
return;
icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
}
/*
* Handle ICMP_ECHO ("ping") requests.
*
* RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
* requests.
* RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
* included in the reply.
* RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
* echo requests, MUST have default=NOT.
* See also WRT handling of options once they are done and working.
*/
static void icmp_echo(struct sk_buff *skb)
{
struct net *net;
net = dev_net(skb_dst(skb)->dev);
if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
struct icmp_bxm icmp_param;
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.data.icmph.type = ICMP_ECHOREPLY;
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = skb->len;
icmp_param.head_len = sizeof(struct icmphdr);
icmp_reply(&icmp_param, skb);
}
}
/*
* Handle ICMP Timestamp requests.
* RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
* SHOULD be in the kernel for minimum random latency.
* MUST be accurate to a few minutes.
* MUST be updated at least at 15Hz.
*/
static void icmp_timestamp(struct sk_buff *skb)
{
struct timespec tv;
struct icmp_bxm icmp_param;
/*
* Too short.
*/
if (skb->len < 4)
goto out_err;
/*
* Fill in the current time as ms since midnight UT:
*/
getnstimeofday(&tv);
icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
tv.tv_nsec / NSEC_PER_MSEC);
icmp_param.data.times[2] = icmp_param.data.times[1];
if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
BUG();
icmp_param.data.icmph = *icmp_hdr(skb);
icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
icmp_param.data.icmph.code = 0;
icmp_param.skb = skb;
icmp_param.offset = 0;
icmp_param.data_len = 0;
icmp_param.head_len = sizeof(struct icmphdr) + 12;
icmp_reply(&icmp_param, skb);
out:
return;
out_err:
ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
goto out;
}
static void icmp_discard(struct sk_buff *skb)
{
}
/*
* Deal with incoming ICMP packets.
*/
int icmp_rcv(struct sk_buff *skb)
{
struct icmphdr *icmph;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
struct sec_path *sp = skb_sec_path(skb);
int nh;
if (!(sp && sp->xvec[sp->len - 1]->props.flags &
XFRM_STATE_ICMP))
goto drop;
if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
goto drop;
nh = skb_network_offset(skb);
skb_set_network_header(skb, sizeof(*icmph));
if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
goto drop;
skb_set_network_header(skb, nh);
}
ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
if (skb_checksum_simple_validate(skb))
goto csum_error;
if (!pskb_pull(skb, sizeof(*icmph)))
goto error;
icmph = icmp_hdr(skb);
ICMPMSGIN_INC_STATS_BH(net, icmph->type);
/*
* 18 is the highest 'known' ICMP type. Anything else is a mystery
*
* RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
* discarded.
*/
if (icmph->type > NR_ICMP_TYPES)
goto error;
/*
* Parse the ICMP message
*/
if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
/*
* RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
* silently ignored (we let user decide with a sysctl).
* RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
* discarded if to broadcast/multicast.
*/
if ((icmph->type == ICMP_ECHO ||
icmph->type == ICMP_TIMESTAMP) &&
net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
goto error;
}
if (icmph->type != ICMP_ECHO &&
icmph->type != ICMP_TIMESTAMP &&
icmph->type != ICMP_ADDRESS &&
icmph->type != ICMP_ADDRESSREPLY) {
goto error;
}
}
icmp_pointers[icmph->type].handler(skb);
drop:
kfree_skb(skb);
return 0;
csum_error:
ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
error:
ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
goto drop;
}
void icmp_err(struct sk_buff *skb, u32 info)
{
struct iphdr *iph = (struct iphdr *)skb->data;
int offset = iph->ihl<<2;
struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
int type = icmp_hdr(skb)->type;
int code = icmp_hdr(skb)->code;
struct net *net = dev_net(skb->dev);
/*
* Use ping_err to handle all icmp errors except those
* triggered by ICMP_ECHOREPLY which sent from kernel.
*/
if (icmph->type != ICMP_ECHOREPLY) {
ping_err(skb, offset, info);
return;
}
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
else if (type == ICMP_REDIRECT)
ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
}
/*
* This table is the definition of how we handle ICMP.
*/
static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
[ICMP_ECHOREPLY] = {
.handler = ping_rcv,